The man, who was working for a Geneva-based international organization in the African country, flew to Geneva where a diagnosis at the university hospital (HUG) showed he had no sign of infection, federal authorities in Bern said.

The doctor, whose citizenship was not disclosed, will nonetheless remain under observation and will be checked regularly over the next three weeks, the maximum time for incubation of the virus.

The federal office for public health said the risk of this person becoming sick was very slight and the Swiss population was not in any danger.

The Geneva-based World Health Organization said on Monday that the recent outbreak of Ebola in west Africa — the deadliest in history — has killed 2,811 people.

Guinea, where the outbreak began early this year, and the neighbouring countries of Liberia and Sierra Leone, have been hardest hit by the virus.

The WHO said cases in Senegal and Nigeria have essentially been contained.

The doctor flown to Geneva was working in a Sierra Leone hospital where on Saturday night he was bitten by a child infected by the Ebola virus.

He did not suffer any visible wound, the federal public health office said.

The office described his return to Switzerland as a precautionary measure, with his flight organized by his employer.

A Swiss federal task force has been working for the past two months on measures to respond to the Ebola crisis, clarifying among other things procedures at the country’s airports and at centres for asylum seekers.